We Asked a Neurologist to Explain the Science of Blacking Out

Think back to that time when you woke up on the floor of your parents' bathroom—or naked in a meadow, or in a stranger's bed, or even in a police station—without the slightest idea how you ended up there. The quasi-social/neurological phenomenon known as "blacking out" has been the lubricant behind many a regrettable late-night text and criminal misdemeanor, but even the most seasoned partiers remain ignorant as to how—and why—it happens.

Luckily, scientists have made strides in recent years to unraveling the mystery of the blackout. Back in 2011, researchers at Washington University came to the conclusion that you don't black out because your brain cells are being destroyed, but rather because your nerve cells are weakened and can no longer store incoming information. In other words, the cells in question stop communicating properly with each other, leading to the dark emptiness that many of us know too well.

To learn a bit more about the subject, we enlisted the help of Dr. Roland Mader, a neurologist and consultant at Vienna's Anton-Proksch Institute. Mader works with a variety of addicts, and understands the power of alcohol on the human brain more than most. Below, he explains the science of the blackout, and how you can prevent one from happening.

THUMP: Why exactly does one blackout?

Dr. Mader: The affect of alcohol on the brain is sedative, because it's poisonous to our cells. When you drink in excess, brain cells stop communicating as fast and precisely with one another. That means less information can be transmitted, which is what causes the blackout.

Are there certain types of alcohol that facilitate having blackouts? Perhaps cheap alcohol?
[Blacking out] doesn't have anything to do with the alcohol's quality. In principle, the more concentrated alcohol is, the more dangerous. So hard drinks facilitate having a blackout more than others. But whether [you drink] gin or vodka doesn't matter. The alcohol's quality does influence the after-effects, and brain activity is temporarily affected. After [the alcohol] is processed, things go back to normal.

Is the likelihood of blacking out contingent on a person's physical condition?
Yes, alcohol always affects the body differently, and each person reacts differently based on external factors. Exhaustion and lots of stress can negatively influence the end result. Also, an empty stomach makes a blackout more likely, because your body absorbs the alcohol faster.

What other factors facilitate having a blackout?
What's especially disadvantageous is drinking too quickly, because then your body is confronted with a higher concentration of alcohol. The worst thing you can do is not eat, and then drink hard alcohol really fast. Blood alcohol content above 0.15 means there's a large chance of a blackout.

Does the probability of having blackouts regularly have anything to do with genetics?
Yes, there are genetic differences that play into one's tolerance of alcohol—it's very individual. More than 50% of [alcohol tolerance] is genetically determined. There are also differences between men and women in terms of how well they can handle alcohol. Women, for example, can on average only handle a third of what men can in terms of alcohol. Additionally, if a mother drinks during pregnancy, the child will have a higher susceptibility for blackouts.

Does mixing different types of alcohol make a difference?
It depends on how concentrated the alcohol is. Mixing drinks has no meaning in terms of blackouts. Still, large amounts of sugar in drinks—such as in cocktails—can be a problem, because the alcohol is absorbed rapidly into the blood with sugar.

How can you prevent having a blackout?
You should definitely drink nonalcoholic drinks from time to time while you're drinking; it's best if you drink a glass of water after each glass of alcohol. You should also stick to less concentrated forms of alcohol and give yourself time. But the most important thing, even if it sounds hackneyed, is to just not drink too much.